Berimbau

Orinally brought to Brazil in the 1500's by Bantù slaves from Africa and used to accompany the famous dance called Capoeira (it's a sort of a martial art were two fighter are trained while berimbau, tambourine and agogo bells play a rhythm).

Berimbau was also a mean of communication used by slaves to prevent to be understood by their bosses and is considered a sacred instrument. Is made by a wooden arc (a special kind of wood called Biriba), a wire from end to end and a gourd (cabassa plant) opened on one side (resonator) attached with a piece of cord at the lower side of the arc (20cm from the bottom).

Moving the gourd back and forth from the abdomen creates a kind of wah-wah effect. You also can vary the "feel" of each sound. To play berimbau You need a stick to strike the wire, a stone or a coin which is held against the wire and one ore more caxixi. Basically, there are three different sound:
 

1. Rattle
   w/ the coin only a few milimeters away from the wire.
   Usually w/ additional emphasis on the caxixi.

2. Low sound 
   only hit the wire below the coin, don't press coin against wire.

3. High sound
   press the coin strongly against the wire.

Moving the gourd back and forth AND changing the position of the coin allows you to create slides between the different notes. The berimbau is also a great instrument to experiment w/ 

CREDITS
Thanks to Lars for providing part of the above info..